CVE-2026-72124

Received Received - Intake

Race Condition in Linux Kernel CAN ISOTP Subsystem

Publication date: 2026-08-15

Last updated on: 2026-08-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: can: isotp: serialize TX state transitions under so->rx_lock The TX state machine (so->tx.state) is driven from three contexts: sendmsg() claiming and progressing a transfer, the RX path consuming Flow Control/echo frames, and two hrtimers timing out a stalled transfer. Mixing a lock-free cmpxchg() claim in sendmsg() with hrtimer_cancel() calls made under so->rx_lock elsewhere left windows where a frame or timer callback could act on a state that had already moved on, corrupting an unrelated transfer. so->rx_lock now covers the full lifecycle of a TX claim: sendmsg() takes it to check so->tx.state is ISOTP_IDLE, switch it to ISOTP_SENDING, bump so->tx_gen and drain the previous transfer's timers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf() already run under this lock via isotp_rcv(), and isotp_rcv_echo() now takes it itself, so none of them can ever observe a transfer mid-claim. This also means a transfer can no longer be handed to sendmsg()'s cleanup paths (signal or send error) while another thread is concurrently claiming or finishing it, so those paths can cancel timers and reset the state unconditionally. isotp_release() claims the socket the same way, so a racing sendmsg() sees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending. Only the hrtimer callbacks stay outside so->rx_lock, since they run under so->rx_lock's cancellation elsewhere and taking it themselves would deadlock. so->tx_gen lets them recognize whether the transfer they timed out is still the one currently active, so they don't report an error against a transfer that has since completed or been superseded.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-19

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-72124

EUVD

EUVD-2026-58882

Affected Vendors & Products

Vendor	Product	Version / Range
linux_kernel	linux_kernel	*
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a race condition in the CAN isotp (ISO-TP) protocol implementation. The TX state machine in the isotp module could be corrupted due to improper locking between sendmsg() and hrtimer callbacks. This allows a frame or timer callback to act on a state that has already changed, potentially corrupting unrelated data transfers.

Detection Guidance

This vulnerability is specific to the Linux kernel's CAN isotp module and requires kernel-level inspection. Detection involves checking kernel logs for related errors or verifying the kernel version against patched releases. Commands like dmesg | grep isotp or checking uname -r for kernel version may help identify affected systems.

Impact Analysis

This vulnerability could lead to data corruption or unexpected behavior in CAN communication systems using the isotp protocol. It may cause crashes, incorrect data transmission, or denial of service in systems relying on CAN networks, such as automotive or industrial control systems.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it pertains to a CAN ISOTP state machine issue in the Linux kernel. No evidence suggests data exposure or privacy violations.

Mitigation Strategies

Apply the latest kernel patches from your Linux distribution to resolve this issue. If immediate patching is not possible, consider disabling the CAN isotp module via modprobe -r isotp or restricting CAN network access until patched.

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